Cast iron and titanium alloys are currently the materials of choice for certain high-temperature applications, such as automotive chassis and transmission components, automotive and aircraft engine components, aircraft engine structural components and airframe structural skins and frames. However, cast dilute aluminum-zirconium-scandium (Al—Zr—Sc) alloys, where scandium and zirconium are below their solubility limits, are excellent alternatives to cast iron and titanium alloys in high temperature applications.
Aluminum-zirconium-scandium alloys offer promising strength and creep resistance at temperatures in excess of 300° C. Aluminum-zirconium-scandium alloys can be affordably produced using conventional casting and heat treatment. Upon aging, supersaturated aluminum-scandium alloys form coherent L12-ordered Al3Sc precipitates, which provide significant strengthening to a temperature of about 300° C. Zirconium is added to aluminum-scandium alloys to form coarsening-resistant Al3(ScxZr1-x) (L12) precipitates, which consist of a scandium-enriched core surrounded by a zirconium-enriched shell. Unfortunately, the high cost of scandium limits the industrial applicability of aluminum-scandium alloys.
Accordingly, those skilled in the art continue with research and development efforts in the field of aluminum alloys.